RESUMO
Unregulated acute inflammation can lead to collateral tissue injury in vital organs, such as the lung during the acute respiratory distress syndrome. In response to tissue injury, circulating platelet-neutrophil aggregates form to augment neutrophil tissue entry. These early cellular events in acute inflammation are pivotal to timely resolution by mechanisms that remain to be elucidated. Here, we identified a previously undescribed biosynthetic route during human platelet-neutrophil interactions for the proresolving mediator maresin 1 (MaR1; 7R,14S-dihydroxy-docosa-4Z,8E,10E,12Z,16Z,19Z-hexaenoic acid). Docosahexaenoic acid was converted by platelet 12-lipoxygenase to 13S,14S-epoxy-maresin, which was further transformed by neutrophils to MaR1. In a murine model of acute respiratory distress syndrome, lipid mediator metabololipidomics uncovered MaR1 generation in vivo in a temporally regulated manner. Early MaR1 production was dependent on platelet-neutrophil interactions, and intravascular MaR1 was organ-protective, leading to decreased lung neutrophils, edema, tissue hypoxia, and prophlogistic mediators. Together, these findings identify a transcellular route for intravascular maresin 1 biosynthesis via platelet-neutrophil interactions that regulates the extent of lung inflammation.
Assuntos
Plaquetas/metabolismo , Ácidos Docosa-Hexaenoicos/biossíntese , Inflamação/metabolismo , Pulmão/metabolismo , Neutrófilos/metabolismo , Animais , Araquidonato 12-Lipoxigenase/metabolismo , Plaquetas/efeitos dos fármacos , Líquido da Lavagem Broncoalveolar/citologia , Hipóxia Celular , Quimiotaxia de Leucócito , Modelos Animais de Doenças , Ácidos Docosa-Hexaenoicos/metabolismo , Ácidos Docosa-Hexaenoicos/farmacologia , Ácidos Docosa-Hexaenoicos/fisiologia , Ácidos Docosa-Hexaenoicos/uso terapêutico , Xenoenxertos , Humanos , Ácido Clorídrico/toxicidade , Inflamação/patologia , Pulmão/efeitos dos fármacos , Pulmão/patologia , Masculino , Metabolômica , Camundongos , Camundongos Endogâmicos BALB C , Estrutura Molecular , Fator de Ativação de Plaquetas/farmacologia , Transfusão de Plaquetas , Proteínas Recombinantes/metabolismo , Síndrome do Desconforto Respiratório/induzido quimicamente , Síndrome do Desconforto Respiratório/tratamento farmacológico , Síndrome do Desconforto Respiratório/metabolismo , Síndrome do Desconforto Respiratório/patologia , Trombina/farmacologiaRESUMO
Rice Hoja Blanca Tenuivirus (RHBV), a negative strand RNA virus, has been identified to infect rice and is widely transmitted by the insect vector. NS3 protein encoded by RHBV RNA3 was reported to be a potent RNAi suppressor to counterdefense RNA silencing in plants, insect cells, and mammalian cells. Here, we report the crystal structure of the N-terminal domain of RHBV NS3 (residues 21-114) at 2.0 Å. RHBV NS3 N-terminal domain forms a dimer by two pairs of α-helices in an anti-parallel mode, with one surface harboring a shallow groove at the dimension of 20 Å × 30 Å for putative dsRNA binding. In vitro RNA binding assay and RNA silencing suppression assay have demonstrated that the structural conserved residues located along this shallow groove, such as Arg50, His51, Lys77, and His85, participate in dsRNA binding and RNA silencing suppression. Our results provide the initial structural implications in understanding the RNAi suppression mechanism by RHBV NS3.